In order to be able to register and track individual containers that are loaded/unloaded to/from a ship, a train, a truck chassis or trailer, containers are given a unique identification (ID) that is marked on an exterior surface of the container. The container identification typically is an alphanumeric code that is marked onto the top-side, front-side, rear-side or a side of the container. In addition to the container identification, other information marked onto the container or attached to the container may be read or recognized each time a container is transferred by a container handling crane. An example of such additional information is the seal attached to container doors, typically at the rear-side of the container. The seal may for instance contain an RFID (Radio-Frequency Identification) tag. Other examples are a class identification or the IMDG (International Maritime Dangerous Goods) code when dangerous or hazardous materials are contained.
United States Patent Application US 2004/0126015 entitled “Container Identification and Tracking System” describes a system for automatically identifying containers that are loaded/unloaded by a crane. The system consists of several cameras fixedly mounted on the sill beams of the crane. These cameras are referenced 13a, 13b and 13c in FIG. 6 of US 2004/0126015 whereas the sill beams of the crane are referenced 12a and 12b. These sill beams are horizontal beams of the container handling crane, typically mounted at a height of 6 meter from the quay in a direction perpendicular to the boom of the crane, i.e. parallel to the quay border. The sill beam mounted cameras create a scan window at a height of 6 meters where the exterior surface of the side of the container can be scanned, typically while the container is vertically moved by the spreader. In order to decide which camera(s) to activate, the system described in US 2004/0126015 contains a camera control system that receives information indicative for the horizontal position where the container will pass, the so called spreader width information in paragraph [0043] of US 2004/0126015.
The sill beam solution is disadvantageous for various reasons as will be explained in the following paragraphs.
Firstly, the container identification becomes available late in the container handling process. The sill beam solution enables to scan and read a container identification only at the point in time where the spreader holding the container passes the window at 6 meter height above the quay where the cameras are located. In case of unloading a container from a ship, the information identifying the container is available very late in the process of transferring the container, i.e. only a few seconds before the container is unlocked from the spreader.
Secondly, the sill beam solution negatively impacts the performance of a container terminal, typically expressed or measured as the amount of moves a crane can make per hour. Since the spreader has to move the container through a fixed window where the cameras are able to scan the container identification, the process of loading/unloading a container is slowed down, which negatively impacts the overall performance of the container terminal.
Thirdly, the sill beam solution is expensive in maintenance since it requires plural cameras. In the implementation illustrated by FIGS. 5 and 6, and described in paragraph [0043] of US 2004/0126015 for instance, three cameras are mounted on each of the sill beams. Since these cameras are operating in difficult conditions resulting from the presence of wind and water in port or railway areas, their lifetime is limited and maintenance requirements are high. Plural cameras mounted on the sill beams consequently increase the installation and operational costs for the container terminal operator.
Further disadvantageously, front-sides and rear-sides of the containers cannot be scanned in the sill beam solution. Since the cameras are mounted on the sill beams, only container identifications marked on the side of the container can be scanned. In case the container identification or other useful information such as the IMDG code or seal is marked on or attached to a front-side or rear-side of the container, the sill beam mounted cameras cannot be used. A straightforward solution enabling to scan front-sides and rear-sides of containers could consists in mounting also cameras on the portal beams of the crane, i.e. the horizontal beams parallel to the boom of the crane at a typical height of 13 to 16 meter from the quay. Such additional cameras however would further increase the installation and maintenance costs for the terminal operator and would further slow down the container handling process since the spreader would have to move the container(s) through a second scan window at a typical height of 13 to 16 meter. An alternative solution enabling to scan front-sides and rear-sides of containers consists in a crane system with rotating flywheel to rotate the container as for instance suggested in U.S. Pat. No. 7,783,003 entitled “Rotating Carriage Assembly for Use in Scanning Cargo Conveyances Transported by a Crane”. Such solution however requires a dedicated type of crane with rotating flywheel and therefore is not applicable to installed cranes that lack such flywheel.
It is further important to notify that there is an evolution towards development and installation of higher cranes. Whereas today's cranes have typical hoisting heights of 30 meters above rail or quay level, next generation cranes will have heights that extend beyond 50 meters. These cranes will be able to operate at different heights. The maintenance or reparation of electronics or components that operate at such heights will become even more difficult, in particular in harbours where the environmental conditions of wind and water are hard. Moreover, the availability of boom trucks that can be used for maintenance purposes and can reach heights above 30 meters is scarce.
International patent application WO 2009/052854 entitled “Device, Method and System for Recording Inspection Data About a Freight Container” describes a container handling crane with cameras movably mounted on a vertical support or horizontal beam. As is specified in WO 2009/052854 on page 3, lines 14-27, the movement of the cameras is controlled by using the container position and speed, obtained from a crane control system.
Although the container scanning system known from WO 2009/052854 aims at scanning the container short sides—see WO 2009/052854, page 2, line 31 to page 3, line 2—and the presence of IMO placards, the door type, door direction, condition of door seal—see page 9, lines 27-32—the system known from WO 2009/052854 is still disadvantageous for several reasons.
Firstly, WO 2009/052854 fails to describe how the cameras are made movable along the vertical supports or horizontal beams of the crane. Straightforward implementations would rely on cables along which the camera would move, or on movable arms that would take the cameras to the desired positions. Such implementations that make use of cables or movable arms however poorly perform in hard environmental conditions resulting from the presence of wind, water and salt in port or railway areas. Straightforward implementations with movable cameras in other words require regular inspection and maintenance as a result of which their downtime and operational costs are high.
Secondly, the system known from WO 2009/052854 does not allow to scan containers that are moved along an optimal path. The optimal path followed by the crane to unload/load a container depends on the origin/destination location of the container on the ship and the destination/origin location of the container on the quay. This optimal path is different for each container: it will be ascending for certain containers near the crane leg where the movable camera is mounted on, whereas it will be descending for other containers near that same leg. As a result of these differences in nature of the optimal paths followed by different containers, merely using the container position and speed to control the position of the camera/sensor is insufficient to guarantee a successful scan. The system known from WO 2009/052854 consequently can only make successful scans when the crane is controlled to deviate from the optimal path as a result of which unloading/loading containers becomes slower and the overall performance of the crane is reduced.
The system known from WO 2009/052854 also is restricted to make a single image at time t+1 (see step 30 in FIG. 2). Only in embodiments where a second camera is provided, a second image can be made of a container side (see steps 210 and 212 in FIG. 4). The system hence has clear technical limitations that can only be resolved at the cost of more cameras/sensors, and the inherent corresponding cost of increased maintenance and downtime.
It is therefore an objective of the present invention to provide a container scanning system that resolves the above identified shortcomings of the prior art. More particularly, it is an objective of the present invention to disclose a container scanning system that scans a container identification or other information marked on or attached to the front-side, rear-side or sides of a container, wherein the scanned information becomes available early in the container handling process, and which enables to increase the overall terminal performance with a less costly and less labour-intensive solution in terms of required electronics and cameras, and with increased reliability. It is in particular an objective of the present invention to disclose a container scanning system with movable cameras that reduces the downtime for maintenance in comparison to straightforward implementations, and that allows the crane to move each container along the optimal unload/load path in order to further optimize the terminal performance. It is a further objective to enable making plural scans without a need to multiply the camera/sensor infrastructure.